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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Precision alignment of an infrared imaging system

The optical hardware design and methods of alignment for the GOES (Geostationary Operational Environmental Satellite) imaging instrument are discussed. The instrument is a multi-channel space-borne meteorological system. Included will be the results of a tolerance and sensitivity analysis for the optics and their adjustment mechanisms. A brief summary of the sequence of system alignment steps taken to achieve the final configuration of the instrument will conclude the discussion.

Kohrman, Richard J.↗
NASA NTRS2018

Laser Metrology for Ultra-Stable Space-Based Coronographs

Sensing starlight rejected from a coronagraph is essential in stabilizing the telescope pointing and wavefront drift, but performance is degraded for dim stars. Laser Metrology (MET) provides a different, complementary sensing method, one that can be used to measure changes in the alignment of the optics at high bandwidth, independent of the magnitude of the host star. Laser metrology measures changes in the separation of optical fiducial pairs, which can be separated by many meters. The principle of operations is similar to the laser metrology system used in LISA-Pathfinder to measure the in-orbit displacement between two test masses to a precision of ~10 picometers. In closed loop with actuators, MET actively maintains rigid body alignment of the front-end optics, thereby eliminating the dominant source of wavefront drift. In the case of a segmented, active primary mirror, MET provides six degrees of freedom sensing, replacing edge sensors. MET maintains wavefront control even during attitude maneuvers, such as slews between target stars, thereby avoiding the need to repeat time-consuming speckle suppression. These features can significantly improve the performance and observational efficiency of future large-aperture space telescopes equipped with internal coronagraphs. We evaluate MET trusses for various proposed monolithic and segmented space-based coronagraphs and present the performance requirements necessary to maintain contrast drift below 10^-11.

Moore, Dustin↗
NASA NTRS1980

Large-aperture high-resolution X-ray collimator for the Solar Maximum Mission

A description is presented of a flight-qualified large-aperture 12 x 12-arcsec angular resolution multigrid X-ray collimator developed for the Solar Maximum Mission (SMM) flat crystal spectrometer. This collimator, designed for the 1.4-22.4-A wavelength range, utilizes an optical bench/metering structure to align and support prealigned grid subassemblies. The optical bench is a lightweight, rigid, and stable aluminum honeycomb structure. The grids are of a compound and bimetallic design, having 63.5-micron square holes on an 88.9-micron spacing in 8-micron thick gold, which is in turn supported by a 76-micron thick Invar grid having 600-micron square holes on a 739-micron spacing. The small apertures in the gold provide the 12-arcsec collimation with the Invar grids providing wide angle off-axis blocking out to an approximately 35 arcmin view angle. The collimator has seven individual channels, four of a 5.1- x 10-cm area and three of a 1.3- x 10-cm area. Laboratory measurements gave an average angular resolution of 12.5 arcsec FWHM with 0.259 transmission for the large-area channels and 12.0 arcsec and 0.200 transmission for the small-area channels. A thermal filter composed of two layers of approximately 1000-A thick aluminum prevents solar heating of the front collimator grids by absorbing longer wavelength radiation while passing most of the X radiation in the band of interest.

Nobles, R. A.↗
NASA NTRS2019

Optical System Design and Integration of the Global Ecosystem Dynamics Investigation Lidar

The Global Ecosystem Dynamics Investigation (GEDI) instrument was designed, built, and tested in-house at NASA’s Goddard Space Flight Center and launched to the International Space Station (ISS) on December 5, 2018. GEDI is a multi-beam waveform LiDAR (light detection and ranging) designed to measure the Earth’s global tree height and canopy density using 8 laser beam ground tracks separated by roughly 600 meters. Given the ground coverage required and the 2 year mission duration, a unique optical design solution was developed. GEDI generates 8 ground sampling tracks from 3 transmitter systems viewed by a single receiver telescope, all while maximizing system optical efficiency and transmitter to receiver boresight alignment margin. The GEDI optical design, key optical components, and system level integration and testing are presented here. GEDI began 2 years of science operations in March 2019 and so far, it is meeting all of its key optical performance requirements and is returning outstanding science.

Integration↗
NASA NTRS2011

Pupil Alignment Considerations for Large, Deployable Space Telescopes

For many optical systems the properties and alignment of the internal apertures and pupils are not critical or controlled with high precision during optical system design, fabrication or assembly. In wide angle imaging systems, for instance, the entrance pupil position and orientation is typically unconstrained and varies over the system s field of view in order to optimize image quality. Aperture tolerances usually do not receive the same amount of scrutiny as optical surface aberrations or throughput characteristics because performance degradation is typically graceful with misalignment, generally only causing a slight reduction in system sensitivity due to vignetting. But for a large deployable space-based observatory like the James Webb Space Telescope (JWST), we have found that pupil alignment is a key parameter. For in addition to vignetting, JWST pupil errors cause uncertainty in the wavefront sensing process that is used to construct the observatory on-orbit. Furthermore they also open stray light paths that degrade the science return from some of the telescope s instrument channels. In response to these consequences, we have developed several pupil measurement techniques for the cryogenic vacuum test where JWST science instrument pupil alignment is verified. These approaches use pupil alignment references within the JWST science instruments; pupil imaging lenses in three science instrument channels; and unique pupil characterization features in the optical test equipment. This will allow us to verify and crosscheck the lateral pupil alignment of the JWST science instruments to approximately 1-2% of their pupil diameters.

Bos, Brent J.↗
NASA NTRS1987

A simplified CARS measurement system for rapid determination of temperature and oxygen concentration

A new spectroscopic concept for the rapid determination of temperature and oxygen concentration by CARS (Coherent Anti-Stokes Raman Spectroscopy) was described. The ratio of two spectral regions in the broadband Q-branch spectrum was detected by photomultipliers in a monochromator, which ratio depends on temperature and species concentration. The comparison of the measured data with theory was made using a flat flame burner and an electric furnace, with reasonable results. Various optical techniques for alignment were introduced including a highly efficient, stable dye oscillator. The combination of the spectroscopic concept and the optical techniques will make the CARS measurement system rapid in data processing and simple in optical parts.

Fujii, Shoichi↗
NASA NTRS1990

Infrared images of distant 3C radio galaxies

J (1.2-micron) and K (2.2 micron) images have been obtained for eight 3CR radio galaxies with redshifts from 0.7 to 1.8. Most of the objects were known to have extended asymmetric optical continuum or line emission aligned with the radio lobe axis. In general, the IR morphologies of these galaxies are just as peculiar as their optical morphologies. For all the galaxies, when asymmetric structure is present in the optical, structure with the same orientation is seen in the IR and must be accounted for in any model to explain the alignment of optical and radio emission.

Eisenhardt, Peter↗
NASA NTRS2006

Theoferometer for the Construction of Precision Optomechanical Assemblies

The increasing difficulty of metrology requirements on projects involving optics and the alignment of instrumentation on spacecraft has reached a turning point. Requirements as low as 0.1 arcseconds for the static, rotational alignment of components within a coordinate system cannot be met with a theodolite, the alignment tool currently in use. A "theoferometer" is an interferometer mounted on a rotation stage with degrees of freedom in azimuth and elevation for metrology and alignment applications. The success of a prototype theoferometer in approaching these metrology requirements led to a redesign stressing mechanical, optical, and software changes to increase the sensitivity and portability of the unit. This paper covers the improvements made to the first prototype theoferometer, characteristic testing, and demonstration of the redesigned theoferometer s capabilities as a "theodolite replacement" and low-uncertainty metrology tool.

Korzun, Ashley M.↗
NASA NTRS1989

Assembly, alignment, and cold focus test methods utilized on CLAES optics

This paper describes the techniques and the equipment used in the assembly and alignment of the Cryogenic Limb Array Etalon Spectrophotometer (CLAES) Telescope and Spectrometer, together with those used to test the system at operating temperatures in order to establish the correct focus for the detector array and other system components. In addition, cryogenic tests were used to determine the stability of the optics over the specified environment, and blur size measurements were performed at operational temperatures.

Dawson, Juan C.↗
DOE OSTI2021

Multifunctional Metal–Oxide Nanocomposite Thin Film with Plasmonic Au Nanopillars Embedded in Magnetic La 0.67 Sr 0.33 MnO 3 Matrix

Searching for multifunctional materials with tunable magnetic and optical properties has been a critical task toward the implementation of future integrated optical devices. Vertically aligned nanocomposite (VAN) thin films provide a unique platform for multifunctional material designs. In this work, a new metal–oxide VAN has been designed with plasmonic Au nanopillars embedded in a ferromagnetic La 0.67 Sr 0.33 MnO 3 (LSMO) matrix. Such Au–LSMO nanocomposite presents intriguing plasmon resonance in the visible range and magnetic anisotropy property, which are functionalized by the Au and LSMO phase, respectively. Furthermore, the vertically aligned nanostructure of metal and dielectric oxide results in the hyperbolic property for near-field electromagnetic wave manipulation. Such optical and magnetic response could be further tailored by tuning the composition of Au and LSMO phases.

36 MATERIALS SCIENCE↗
NASA NTRS2016

Development and Implementation of a Generic Analysis Template for Structural-Thermal-Optical-Performance Modeling

Performance-related effects of system level temperature changes can be a key consideration in the design of many types of optical instruments. This is especially true for space-based imagers, which may require complex thermal control systems to maintain alignment of the optical components. Structural-Thermal-Optical-Performance (STOP) analysis is a multi-disciplinary process that can be used to assess the performance of these optical systems when subjected to the expected design environment. This type of analysis can be very time consuming, which makes it difficult to use as a trade study tool early in the project life cycle. In many cases, only one or two iterations can be performed over the course of a project. This limits the design space to best practices since it may be too difficult, or take too long, to test new concepts analytically. In order to overcome this challenge, automation, and a standard procedure for performing these studies is essential. A methodology was developed within the framework of the Comet software tool that captures the basic inputs, outputs, and processes used in most STOP analyses. This resulted in a generic, reusable analysis template that can be used for design trades for a variety of optical systems. The template captures much of the upfront setup such as meshing, boundary conditions, data transfer, naming conventions, and post-processing, and therefore saves time for each subsequent project. A description of the methodology and the analysis template is presented, and results are described for a simple telescope optical system.

Scola, Salvatore↗
NASA NTRS1997

Deep WFPC2 and Ground-Based Imaging of a Complete Sample of 3C Quasars and Galaxies

We present the results of an HST and ground-based imaging study of a complete 3C sample of zeta approx. equal to 1 sources, comprising 5 quasars and 5 radio galaxies. We have observed all of the sample in essentially line-free bands at rest-frame 0.33 micrometers with WFPC2 and in rest-frame 1 micrometer images from the ground; we have also observed most of the sample in narrow-band filters centered on [O II]. We resolve continuum structure around all of our quasars in the high-resolution WFPC2 images, and in four of the five ground-based K' images. All of the quasars have some optical continuum structure that is aligned with the radio axis. In at least 3 of these cases, some of this optical structure is directly coincident with a portion of the radio structure, including optical counterparts to radio jets in 3C212 and 3C245 and an optical counterpart to a radio lobe in 3C2. These are most likely due to optical synchrotron radiation, and the radio and optical spectral indices in the northern lobe of 3C2 are consistent with this interpretation. The fact that we see a beamed optical synchotron component in the quasars but not in the radio galaxies complicates both the magnitude and the alignment comparisons. Nonetheless, the total optical and K' flux densities of the quasar hosts are consistent with those of the radio galaxies within the observed dispersion in our sample. The distributions of K' flux densities of both radio galaxies and quasar hosts exhibit similar mean and dispersion to that found for other radio galaxies at this redshift, and the average host galaxy luminosity is equivalent to, or a little fainter than, L*. The formal determination of the alignment in the optical and infrared in the two subsamples yields no significant difference between the radio galaxy and quasar subsamples, and the quasars 3C 196 and 3C 336 have aligned continuum and emission-line structure that is probably not due to beamed optical synchrotron emission. Very blue and/or edge-brightened structures are present in some objects within the probable quasar opening angle; these are possibly the result of illumination effects from the active nucleus, i.e., scattered quasar light or photoionization. In 3C 212, we see an optical object that lies 3 min. beyond the radio lobe, but which looks morphologically quite similar to the radio lobe itself. This object is bright in the infrared and has a steep spectral gradient along its length. A striking, semi-circular arc seen associated with 3C 280 may possibly be a tidal tail from a companion, enhanced in brightness by scattering or photoionization. In the near-infrared, most of the radio galaxies have elliptical morphologies with profiles that are well-fit by de Vaucouleurs r(exp 1/4)-laws and colors that are consistent with an old stellar population. All components around the quasars have optical-infrared colors that are redder than or similar to the colors of their respective nuclei; this is more consistent with a stellar origin for the emission than with a dominant scattering contribution. From the correspondence between the total magnitudes in the galaxies and quasars and the detection of aligned components in the quasars, we conclude that this study provides general support for the unification of FR II radio galaxies and quasars. Some of the objects in the sample (e.g, 3C 212) have properties that may be difficult to explain with our current understanding of the nature of FR II radio sources and the alignment effect.

Ridgway, Susan E.↗
DOE OSTI2022

Polarization-dependent conversion efficiency of carbon nanotube-Si heterojunction solar cells based on aligned carbon nanotube films

We have fabricated solar cells that implement heterojunctions of Si and aligned carbon nanotube (CNT) films. Polarization-dependent optical absorption of highly aligned CNTs led to polarization-dependent conversion efficiencies, which in turn provided insight into the role of the CNT layer in the power generation mechanism in these heterojunction solar cells. When the incident light polarization was parallel to the CNT alignment direction so that the light absorption in the CNT layer was maximized, the short circuit photocurrent decreased by ~25%. This indicates that electron–hole pair generation in the CNT layer does not directly lead to power generation and that the CNT-Si heterojunctions in our devices are Schottky junctions rather than p–n junctions.

Physics↗
NASA NTRSDate not supplied

Camera Calibration and Alignment Metrology at Johnson Space Center’s Electro-Optics Laboratory

It is increasingly common to see spacecraft equipped with cameras for the purpose of navigation. Images are either sent to Earth or processed autonomously on-board to provide information about the vehicle’s position, velocity, and/or attitude. These can be images of stars or celestial bodies for absolute navigation, or images of another spacecraft for relative navigation. While monocular cameras do not provide range information, the images they capture can be processed to determine bearing vectors to target objects within the camera’s field of view. For a camera to be effective in navigation, it must be carefully calibrated and aligned. This involves accurately modeling the optical effects that govern the projection of line-of-sight directions onto the camera’s pixels and determining the camera’s orientation relative to the spacecraft’s reference frame. Engineers at Johnson Space Center’s Electro-Optics Lab regularly perform camera inspection, calibration, and alignment metrology. This was done for the Orion Optical Navigation (OpNav) Camera, the Orion Docking Camera (DCAM), and for numerous cameras belonging to commercial partners. The nature of optical navigation means that cameras must be well-calibrated and their attitude well understood to provide high accuracy bearing measurements to the navigation filter. The stringent accuracy requirements for Orion could not have been met using traditional checkerboard camera calibration or by simply relying on design drawings. This paper details the hardware, software, techniques, and algorithms used by the EOL team to achieve this level of accuracy.

Paul D Mckee↗
NASA NTRSDate not supplied

Camera Calibration and Alignment Metrology at Johnson Space Center’s Electro-Optics Laboratory

It is increasingly common to see spacecraft equipped with cameras for the purpose of navigation. Images are either sent to Earth or processed autonomously on-board to provide information about the vehicle’s position, velocity, and/or attitude. These can be images of stars or celestial bodies for absolute navigation, or images of another spacecraft for relative navigation. While monocular cameras do not provide range information, the images they capture can be processed to determine bearing vectors to target objects within the camera’s field of view. For a camera to be effective in navigation, it must be carefully calibrated and aligned. This involves accurately modeling the optical effects that govern the projection of line-of-sight directions onto the camera’s pixels and determining the camera’s orientation relative to the spacecraft’s reference frame. Engineers at Johnson Space Center’s Electro-Optics Lab regularly perform camera inspection, calibration, and alignment metrology. This was done for the Orion Optical Navigation (OpNav) Camera, the Orion Docking Camera (DCAM), and for numerous cameras belonging to commercial partners. The nature of optical navigation means that cameras must be well-calibrated and their attitude well understood to provide high accuracy bearing measurements to the navigation filter. The stringent accuracy requirements for Orion could not have been met using traditional checkerboard camera calibration or by simply relying on design drawings. This paper details the hardware, software, techniques, and algorithms used by the EOL team to achieve this level of accuracy.

Paul McKee↗
NASA NTRS2001

Preliminary Investigation of an Active PLZT Lens

The design, analysis and preliminary testing of a prototype Adjustable Focus Optical Correction Lens (AFOCL) is described. The AFOCL is an active optical component composed of solid state lead lanthanum-modified zirconate titanate (PLZT) ferroelectric ceramic with patterned indium tin oxide (ITO) transparent surface electrodes that modulate the refractive index of the PLZT to function as an electro-optic lens. The AFOCL was developed to perform optical re-alignment and wavefront correction to enhance the performance of Ultra-Lightweight Structures and Space Observatories (ULSSO). The AFOCL has potential application as an active optical component within a larger optical system. As such, information from a wavefront sensor would be processed to provide input to the AFOCL to drive the sensed wavefront to the desired shape and location. While offering variable and rapid focussing capability (controlled wavefront manipulation) similar to liquid crystal based spatial light modulators (SLM), the AFOCL offers some potential advantages because it is a solid-state, stationary, low-mass, rugged, and thin optical element that can produce wavefront quality comparable to the solid refractive lens it replaces. The AFOCL acts as a positive or negative lens by producing a parabolic phase-shift in the PLZT material through the application of a controlled voltage potential across the ITO electrodes. To demonstrate the technology, a 4 mm diameter lens was fabricated to produce 5-waves of optical power operating at 2.051 micrometer wavelength. Optical metrology was performed on the device to measure focal length, optical quality, and efficiency for a variety of test configurations. The data was analyzed and compared to theoretical data available from computer-based models of the AFOCL.

Lightsey, W. D.↗
DOE OSTI2023

Magnetic self-mating fiber optic connector and fiber optic switch sensor

A system or method for a magnetic self-aligning coupling device for a fiber optic cable. The device includes a first end coupling comprising a first magnet and a second magnet. Both magnets include a mating surface and an annular ring defining an axial aperture. The aperture receives a distal end of a segment of fiber optic cable in a tight fit. The fiber optic cable has an exterior sleeve and a fiber core. The fiber core of the first segment and the second segment of the fiber optic cable are axially aligned by magnetic force in the first and second apertures to create a continuous fiber optic path. A method for detecting a security breach of a door using the self-aligning couplings is also described.

Neidigk, Stephen↗
DOE OSTI2024

Magnetic self-mating fiber optic connector and fiber optic switch sensor

A system or method for a magnetic self-aligning coupling device for a fiber optic cable. The device includes a first end coupling comprising a first magnet and a second magnet. Both magnets include a mating surface and an annular ring defining an axial aperture. The aperture receives a distal end of a segment of fiber optic cable in a tight fit. The fiber optic cable has an exterior sleeve and a fiber core. The fiber core of the first segment and the second segment of the fiber optic cable are axially aligned by magnetic force in the first and second apertures to create a continuous fiber optic path. A method for detecting a security breach of a door using the self-aligning couplings is also described.

Neidigk, Stephen↗